Reference is made to our prior issued U.S. Pat. No. 5,741,250, whose contents are incorporated herein by reference. This prior patent describes an improved myringotomy surgical procedure involving an incision of the tympanic membrane that is made to allow ventilation of the middle ear, to permit drainage of middle ear fluid, or to obtain cultures from an infected middle ear. The improved procedure uses a solid wire electrode and electrosurgical apparatus to form the hole in the tympanic membrane. The electrosurgical procedure has the important advantage of being able to cut the tissue while at the same time coagulating the cut tissue causing minimum bleeding. The structure of the novel electrode described in the prior patent used to make the incision prevents the excision depth from exceeding a safe value. In accordance with another feature of that invention, the electrode is uniquely configured to enable the active tip to reach the tympanic membrane via the ear canal passageway and incise the desired tissue while avoiding damage to surrounding tissue. The procedure, which has come to be known as radiofrequency assisted tympanostomy (RAT), has so far proven to be safe, cost-effective, and can be performed in an office setting. The opening created by the procedure is reasonably precise, bloodless, and can be carried out in less than one second under topical anesthetic.
Recently, a new treatment called OtoScan Laser Assisted Myringotomy (OtoLAM) has been described. It uses a CO2 laser to vaporize an allegedly precisely-sized preset hole in the tympanic membrane without damaging surrounding structures. The preset hole remains open for several weeks allowing ventilation of the middle ear and avoiding the need for grommets to keep the hole open until the middle ear region is adequately drained. The main disadvantage of this procedure is the use of a highly expensive laser instrument requiring training for those physicians that are not familiar with such equipment.
Our prior filed patent application, Ser. No. 09/435,677, whose contents are incorporated herein by reference, describes an improved electrode for a myringotomy surgical procedure comprising a hollow tube with a sharpened edge or a conically pointed electrode dimensioned to produce a desired hole size.
Our prior filed patent application, Ser. No. 09/483,993, whose contents are incorporated herein by reference, describes an improved electrode for a myringotomy surgical procedure comprising a bare end having a sharp circular edge. In another embodiment, the bare end is solid and has a tapered cone shape. When the electrode end is placed against the tympanic membrane and the electrosurgical apparatus activated, a 2 mm hole is punched in the tympanic membrane which allows any middle ear fluid to drain.
An object of the invention is a further improved electrosurgical electrode adapted for use in a myringotomy surgical procedure, as well as the myringotomy procedure using the new electrode.
The present invention is a continuation-in-part of the prior pending applications and hereby incorporates by reference the total contents of the prior applications. The present invention describes an additional electrode for use in a myringotomy surgical procedure but otherwise makes use of the same teachings of the prior applications, and for this reason it was felt unnecessary to repeat in the body of this specification the total contents of the prior applications. The present description will be confined solely to the differences in the electrode ends to achieve certain benefits that may be more difficult to achieve with the electrode constructions of the prior application.
The procedure using our novel electrosurgical electrode of the present invention 5 is based on forming a hole in the tympanic membrane, preferably of approximately 1.5-3 mm in size, which is large enough to remain open to allow adequate drainage from the middle ear over several weeks, but not too large so as to delay healing. It is also possible to insert a tube in the hole to maintain it open while it is healing.
In a preferred embodiment, a unipolar electrode is used with a flared conical tip which is supported in an electrically-insulated shaft. The result when applied against the tympanic membrane is to vaporize a hole in the membrane, by the flow of unipolar electrosurgical currents between the flared conical tip and the tissue. This is in contrast with the action of the other myringotomy punch electrodes which act more like a cookie cutter. The main advantage of the invention is that the possibility of the cut tissue disc formed by the myringotomy punch electrode falling behind the tympanic membrane into the ear drum is avoided. The hole formed by vaporization is essentially of the same size as the outer diameter of the electrode tip. Further advantages include better visualization by the surgeon, especially from the side; reproducible ablation or vaporization quality; and a minimal necrosis zone which provides more predictable healing time and scar-free tissue closing.
In comparison with the laser procedure, the electrosurgical equipment is far less expensive and many physicians are already trained in the use of electrosurgical apparatus. Moreover, for those untrained, the training procedure is relatively simple and consumes little time.
As described in the prior patent, the electrode of the invention is also configured to enable the active tip to reach the tympanic membrane via the ear canal passageway and punch the desired tissue hole while avoiding damage to surrounding tissue.
In accordance with the present invention, the incision is effected with the bare flared conical end moved by the surgeon in a generally straight path, and the adjacent portions of the hollow end support and electrode shaft are made insulating to prevent accidental burns to the patient and to allow the physician to use these insulated parts to help position and guide the active tip portion during the surgical procedure. The electrosurgical procedure has the usual advantage of being able to form the tissue hole while at the same time coagulating the tissue edges causing minimum bleeding. It is preferred that the electrosurgical currents used be above 2 MHz, and preferably above 3 MHz. 3.8-4.0 MHz is preferred. At these higher frequencies, commonly referred to as radiosurgery, the hole is formed by volatilizing intracellular fluids at the point of the transmitting electrode contact which is primarily responsible for only small lateral heat spread and thus less damage to neighboring cell layers.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there are illustrated and described the preferred embodiments of the invention, like reference numerals or letters signifying the same or similar components.